Amazing basement under the floors of an old house. So built or traces of a flood?

Could not stay away from the mid – 19th century version of the flood. In a nutshell, there is a category of people who call themselves alternative historians. According to their conclusions about 1840 on the territory of the planet Earth there was a cataclysm that led to the flooding of most of it. One of the proofs of this flood, in their opinion, is considered to be the first floors of old houses, covered almost completely. Official history says it was built like this. Who is right is difficult to say.
I as the Builder decided to try to understand this question. Took the camera and went for a walk around the city of Ufa. My walks can be seen on video in YouTube.
I present to you the first walk on this topic.

Who is interested can subscribe to my channel. I will continue this topic. Well, the movie about the construction can also be useful to someone)